1256661 has 32 divisors (see below), whose sum is σ = 2182400. Its totient is φ = 699840.

The previous prime is 1256659. The next prime is 1256681. The reversal of 1256661 is 1666521.

It is a happy number.

It is not a de Polignac number, because 1256661 - 2¹ = 1256659 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

Its product of digits (2160) is a multiple of the sum of its prime divisors (180).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1256611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11475 + ... + 11583.

It is an arithmetic number, because the mean of its divisors is an integer number (68200).

2^1256661 is an apocalyptic number.

It is an amenable number.

1256661 is a deficient number, since it is larger than the sum of its proper divisors (925739).

1256661 is a wasteful number, since it uses less digits than its factorization.

1256661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186 (or 180 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 1256661 is about 1121.0089205711. The cubic root of 1256661 is about 107.9127381551.

It can be divided in two parts, 125 and 6661, that added together give a triangular number (6786 = T₁₁₆).

The spelling of 1256661 in words is "one million, two hundred fifty-six thousand, six hundred sixty-one".